8PCS 12V 1-CH Relay Module Optocoupler High/Low Trigger for Arduino | 8PCS 12V 1-channel relay modules with optocoupler isolation, support high/low level trigger, stable & reliable for Arduino.

No wiring schematic included, but available on line

So far I have used these is several projects controlling lamps, valves, attic light....even the shop radio. Super easy to use and so far have been very reliable. I really like that you can send a ground or 5vdc to energize these, so there's lots of projects that don't have microprocessors, just some photo transistors or other sensors. These are truly handy, get several.

These are great because they have the built-in droid that protects against flyback voltage. I use these quite a bit. I have not had one break yet.

I'm using these with Arduino for controlling AC power to model railroad track sections, crossing signals, track switches control, and the like. After using these for a month or so I starting seeing problems with occasional contacts sticking, and thought I had damaged some of the relays. I then discovered the need for snubbers, and after installing them across the relays they all have been working perfectly for the past 4 months.

Pleased with performance.

Very happy so far. Have two of these in a box under the hood of my fj40 for a few weeks. Time will tell, at the price cant complain

I was using this to control some lighting. 120VAC at <1.5 Amps and the contacts would weld closed every 5 or so actuations. A rap with a screwdriver would reset.

Very nice. The only issue I wish they made the wire clamps bigger for 14 gauge wire. It fits it’s just a bit tight. But they work great.